Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2006
Publication Date: 5/15/2006
Citation: Pareek, R.S., Bond, J., Watson, A., Dowd, S.E., McFadden, T., Kerr, D. 2006. Affymetrix GeneChip-based analysis of the genomic response to acute LPS-induced bovine mastitis [abstract]. 2nd International Symposium on Animal Functional Genomics, May 16-19, 2006, Michigan State University. Available: http://www.eb2006-online.com/pdfs/006709.PDF?PHPSESSID=f07543fef8761587d860af5e0239a3bf
Technical Abstract: The genomic response of the bovine mammary gland was profiled four hours after an intramammary challenge with E. coli endotoxin (LPS). Three mid-lactation cows were challenged in one quarter with 1 ug of LPS while contralateral quarters received saline and served as within animal controls. RNA from tissue biopsy samples was interrogated with bovine genome arrays (Affymetrix) that contain more than 23,000 probe sets. We identified 658 genes having differential expression (P<0.01) and fold change >2. Of these probe-sets, 89% were upregulated. Permutation of any control-treatment pairs reduced this number below four, indicating that these hits are not due to uncorrelated variation. Gene ontology analysis demonstrated that a function in immune response, more specifically cytokine and chemokine genes, were nonrandomly represented among these up-regulated genes. Additional GO categories that were over represented in the significant gene list included apoptosis and caspase activity indicating a role for programmed cell death in the biological processes that underlie LPS-induced mastitis and subsequent infection. Independent confirmation of induced expression for IL-8 (89-fold), CXCL2 (75 fold), S100A9 (29-fold), S100A12 (18-fold), and lysozyme (8-fold) was achieved using quantitative real-time RT-PCR (qRT-PCR). A lack of induction of CD14 was confirmed by qRT-PCR, and illustrates a species difference in comparison to similar studies in a mouse model where this LPS-binding protein was markedly induced. In a separate experiment, expression of these genes was examined by qRT-PCR analysis of RNA from epithelial cell cultures that had been exposed, or not, to LPS for six hours. Although lysozyme and S100A12 were not induced, the other genes, IL-8, CXCL2, and S100A9, were markedly induced (greater than 15 fold), lending support to a major role played by the epithelial cell in the acute tissue response to LPS.